In order to determine a terrestrial quality of a mobile communications network, measurement vehicles are used to perform “drive tests” in which measurements are repeatedly carried out along a predetermined driving route using mobile communications receivers provided in the measurement vehicle. As measurements, voice connections and/or data connections are established to different destinations in order to use a measured call setup time or speed of an Internet connection to draw conclusions about the quality of the mobile communications network used. In order to design the measurements to be as realistic as possible, mobile phones that are commercially available to end users are employed as the mobile communications receivers, and these are often connected to antennas arranged outside the measurement vehicle.
Nowadays, unmanned aerial vehicles are being used increasingly for a vastly varied range of uses, for instance for delivering goods or medical supplies in inaccessible terrain. Regulations stipulate that the unmanned aerial vehicles, known as UAVs or drones, are normally allowed to be flown only in visual navigation under line of sight, LOS, between a pilot of the unmanned aerial vehicle and the unmanned aerial vehicle. Numerous applications require autonomous operation, however, in which the unmanned aerial vehicle is flown without LOS, under what is known as NLOS. In such a case, the pilot only makes contact when required, while the unmanned aerial vehicle otherwise flies completely autonomously.
The pilot normally controls the unmanned aerial vehicle by a control device, also called a remote control, which communicates with the unmanned aerial vehicle by means of radio signals. For cost reasons alone, a link to a terrestrial mobile communications network is desirable for autonomous operation of the unmanned aerial vehicle in order for the pilot to be able to make necessary contact when required via the mobile communications connection. This requires, however, that the unmanned aerial vehicle maintains a continuous connection to the terrestrial mobile communications network during its entire flight route comprising frequently changing flight heights and speeds.
Yet until now, little has been known of the quality of terrestrial mobile communications networks at different heights, because the mobile communications networks are planned solely on the basis of terrestrial measurements, for instance on the basis of the results of the drive test described above. Nonetheless, it can be expected in future that the legislature will give clearance to autonomous air traffic of unmanned aerial vehicles in designated and suitably qualified air corridors. In these air corridors, continuous provision by a terrestrial mobile communications network would have to be guaranteed at different heights and speeds in order to avoid dangerous flight situations for the unmanned aerial vehicles.